Preparação e caracterização estrutural e elétrica de células solares sensibilizadas por corantes empregando anodos nanoestruturados à base de 'TiO IND. 2'

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Degradação fotocatalítica de efluente simulado de refinaria de petróleo e monitoramento de sua toxicidade com microrganismos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Indicadores na estimativa do fluxo de nutrientes no duodeno, produção fecal, consumo de concentrado e volumoso por bovinos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Preparação de espumas cerâmicas de 'TIO IND. 2' a partir do processo sol-emulsão-gel

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Desenvolvimento e otimização de materiais nanocristalinos para células solares sensibilizadas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudos e aplicações da célula fotovoltaica DSC

The solar energy is far the largest source of energy available in earth and has attracted for milleniuns, the attention and interest for a rational use. The solar energy which strikes the Earth in one hour is bigger than the whole consume of energy in Earth in one year. Among the forms of transformation of this clean, renewable energy, the electrical conversion, photovoltaic cells, have the materials based on silicon or germanium semiconductors due to its technology and production processes involved still have a high production cost. An alternative to this solar cell is based on a synthetic dye and a semiconductor nanocrystalline TiO2, titanium dioxide, called DSC (Dye-Sensitized Cells), which have a cost of up to 80% lower than silicon cells

Photocatalytic and photoelectrochemical inactivation of Escherichia coli and Staphylococcus aureus

Water disinfection usually requires expensive chemicals or equipment. Chlorination is a common disinfection method, although it is not able to inactivate all pathogens. High concentrations of residual chlorine also cause an unpleasant taste and smell in drinking water. As an alternative, photocatalysis and photoelectrochemical treatment has a high disinfection potential in drinking water by using solid catalysts, such as titanium dioxide. Highly reactive hydroxyl radical generated during the process serves as the main oxidant, capable of inactivating a wide range of microorganisms. In this study, we proposed a novel comparison between Gram-positive and gram-negative microorganisms. An immobilized TiO2 film promoted higher efficiency in water disinfection processes. The treatment effectively inactivated Escherichia coli and Staphylococcus aureus bacterial microorganisms in a shorter period than other alternative methods.

All sol-gel electrochromic smart windows: CeO2-TiO 2/Ormolyte/WO3

A solid state system having the configuration WO 3/Ormolyte/CeO2-TiO2 has been assembled. Syntheses routes for tungsten oxide WO3, and cerium-titanium CeO 2-TiO2 oxide sols, were developed. A novel solid electrolyte - Ormolyte is reported, which were obtained by the sol-gel process, they have a chemical stability due to the covalent bonds between the inorganic and organic phase, and were prepared with different [O]/[L] ratios, being the best for [O]/[L]=15. The variation of transmittance of the electrochromic device using the ormolyte [O]/[L]=15 was 35% (colored state) and 77% (bleached state).

Structural study of copper oxide supported on a ceria-modified titania catalyst system

A structural study of CuO supported on a CeO2-TiO2 system was undertaken using X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) techniques. The results of XRD revealed the presence of only two phases, TiO2 anatase and CeO2 cerianite. A trend towards smaller TiO2 crystallites was observed when cerium content increased. When the amount of cerium increased, Ti K-edge XANES analysis showed an increasing distortion of Ti sites. The results of Ce LIII-edge EXAFS showed that Ce atoms are coordinated by eight oxygen atoms at 2.32 Å. For the sample containing a small amount of cerium, the EXAFS analysis indicated that the local structure around Ce atoms was highly distorted. The catalysts presented quite different Cu K-edge XANES spectra compared to the spectra of the CuO and Cu2O reference compounds. The Cu-O mean bond length was close to that of the CuO and the Cu atoms in the catalysts are surrounded by approximately four oxygen atoms in their first shell. Copper supported on the ceria-modified titania support catalysts displayed a better performance in the methanol dehydrogenation when compared to copper supported only on titania or on ceria. © 2002 Plenum Publishing Corporation.

Photocatalytic decomposition of rhodamine-b using scandium and silver-modified TiO2 powders

Semiconductor-mediated photocatalytic oxidation is an interesting method for water decontamination and a specially modified TiO2 is said to be a promising material. This study verified that the synthesis of 1wt%Ag modified-Sc0.01Ti0.99O1.995 powder samples prepared by Polymeric Precursor Method is capable of forming a mixture of anatase-rutile phase with high photocatalytic performance. This kind of material is found to have a lower bandgap compared to the TiO2-anatase commercial powders, which can be associated to an innovative hybrid modification. The simultaneous insertion of scandium in order to generate a p-type semiconductor and a metallic silver nanophase acting as an electron trapper demonstrated being capable of enhancing the degradation of rhodamine B compared to the commercial TiO2. In spite of the different thermal treatments or phase amounts, the hybrid modified powder samples showed higher photocatalytic activity than the commercial ones.

Synthesis and characterization of nanostructured TiO2-SnO2 composite

Nanostructured composites based on titanium dioxide have been studied in order to improve optical and photo-catalytic properties, as well as their performance in gas sensors. In this work, titanium and tin dioxides were simultaneously synthesized by the polyol method resulting in TiO2 platelet coated with SnO2 nanoparticles as was observed by scanning electron microscopy. The thermal analysis showed that the combined synthesis promotes more easily the crystallization of the TiO2 rutile phase. The composite obtained after heat treatment at 500 °C showed to be formed of almost only rutile phases of both oxides. The optical properties analyzed by UV-Vis spectroscopy showed that the combined oxides have higher absorbance, which reinforces a model found in the literature based on the flow of photo-generated electrons to the conduction band of SnO2 delaying the recombination of charges.

Effect of Chemical Disinfection and Accelerated Aging on Color Stability of Maxillofacial Silicone with Opacifiers

Purpose: The purpose of this study was to evaluate the color stability of MDX4-4210 maxillofacial elastomer with opacifier addition submitted to chemical disinfection and accelerated aging.Materials and Methods: Ninety specimens were obtained from Silastic MDX4-4210 silicone. The specimens were divided into three groups (n = 30): Group I: colorless, Group II: barium sulfate opacifier, Group III: titanium dioxide opacifier. Specimens of each group (n = 10) were disinfected with effervescent tablets, neutral soap, or 4% chlorhexidine gluconate. Disinfection was conducted three times a week for 2 months. Afterward, the specimens were submitted to different periods of accelerated aging. Color evaluation was carried out after 60 days (disinfection period) and after 252, 504, and 1008 hours of accelerated aging, using a reflection spectrophotometer. Color alterations were calculated by the CIE L*a*b* system. Data were analyzed by three-way ANOVA and Tukey test (alpha = 0.05).Results: Group II exhibited the lowest color change, whereas Group III the highest (p < 0.05), regardless of the chemical disinfection and accelerated aging periods.Conclusion: Opacifier addition, chemical disinfection, and accelerated aging procedures affected the color stability of the maxillofacial silicone.

Influence of opacifiers on dimensional stability and detail reproduction of maxillofacial silicone elastomer

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Spectrophotometric determination of diclofenac in pharmaceutical preparations assisted by microwave oven

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

DESENVOLVIMENTO DE UMA ESCALA em SILICONA PARA TONS DE PELE HUMANA

O autor desenvolveu em silicona uma escala de tonalidades de pele humana. Foram confeccionados vinte e sete corpos-de-prova em silicona acética (Silastic 732 RTV), pigmentados com óxidos de ferro e dióxido de titânio. A quantidade de silicona acética manteve-se constante (dois gramas) em todos os corpos-de-prova, e os pigmentos foram misturados a ela em várias proporções até a obtenção de vinte e sete diferentes tonalidades. Através da comparação da cor dos corpos-de-prova com a cor da pele de quarenta e um indivíduos, foram selecionados os cinco corpos-de-prova com as tonalidades que mais se igualavam à cor da pele dos pacientes, compondo, assim, um guia de tonalidades. Com a metodologia empregada, foi possível desenvolver uma escala de tonalidades de pele que poderá facilitar a definição do tom da pele do paciente quando da confecção de próteses faciais em silicona, permitindo economia de tempo e de material no momento da seleção da cor.